The global pandemic unleashed by the new human coronavirus has put the economies and health systems of many Western countries in check. A crisis that reminds us that we are one more species on the planet and that, despite technological progress and accumulated knowledge, we find ourselves at the mercy of many factors that we do not control. In this case, we are talking about a virus, an entity of nanometric dimensions and that even, according to the criteria used, could not even be considered as a living being.
There are a number of defining characteristics of life, and viruses are on that slippery border between what is alive and what is not. Standard definitions of viruses tell us that they are genetic elements that need a cell (called a host) to replicate. In addition, they have an extracellular phase that allows them to be easily transmitted from one host to another, and this form causes some viruses to replicate in a host in such a way that they end up being destructive to cells and causing disease.
So we have a structure that, on the one hand, is not self-sufficient to replicate its genetic material, but on the other, it complies with the so-called ‘central dogma of molecular biology’: information flows from nucleic acid (genetic material) to the protein.
So are we talking about living beings? “The same thing happens with viruses as when physicists talk about the dual nature of light: is it a wave or is it a particle? Well, it depends ”, explains José Aguilar Gavilán, researcher and professor of virology at the University of Córdoba. “Life is manifested by any being that can express its genetic heritage. When a virus is manifesting its genetic information, that is, when it is within the cell expressing itself, I can consider it a living being , very simple and straightforward, but a living being after all ”.
What happens when the virus does not express its genetic material? ” When the virus is in a latent state, either inside or outside the cell, it is not considered a living being but a super-complex organic molecule “, explains the expert. “In other words, in this state, which is called the static phase, the virus does not express itself, and there it is not considered a living being. Now, when it is in a dynamic phase and is multiplying, you can say with all the laws that it is a living being, the only thing that happens is that it is a genetic parasite, that is, it has to parasitize the genetic machinery of the cell ”, concludes the researcher.
A little history
The Brock Handbook. Biology of microorganisms tells in his chapter dedicated to viruses that the original meaning of this word included any toxic substance, such as the venom of a snake, and that it was later used more specifically to designate the etiological agent of all infectious disease. In fact, Pasteur often referred to the bacteria that cause specific infectious diseases as viruses.
Although Dmitri Ivanovski is widely cited as the father of virology, the truth is that there were several scientists who contributed to the first knowledge about viruses when they realized that they were facing pathogens with characteristics very different from bacteria. In 1898, for example, Friedrich Loeffler and Paul Frosch had found evidence that foot-and-mouth disease was due to an agent so small that it was able to pass through the filters that retained all the bacteria until then known. The concept of “filterable agent” then emerged , and Ivanovski demonstrated in his experiments with what we now know to be the tobacco mosaic virus that the etiological agent that caused it also passed through the filters. In turn, Martinus Beijerinck went a step further by showing that this infectious agent exhibited some properties characteristic of living organisms.
The virology of the 21st century has evolved a lot since those first observations from leaks, but they undoubtedly laid the foundations for the study of viruses . Thanks to these investigations and many others that came later today, it is possible that laboratories around the world are advancing at great speed to search for treatments and vaccines that help us alleviate the ravages of the COVID-19 epidemic.
